1. Field of the Invention
The present invention relates to a head slider accommodated in a recording medium drive such as a hard disk drive (HDD), in particular, to a flying head slider comprising a slider body, a generally flat bottom surface defined on the slider body, a front rail standing on the bottom surface at an upstream or windward position, and an air bearing surface defined on the front rail.
2. Description of the Prior Art
A load/unload mechanism employing a ramp is well known in the technical field of a magnetic disk drive such as a hard disk drive (HDD). The ramp is designed to support an elastic head suspension, carrying a head slider at the tip end, when a magnetic recording disk stands still. For example, the ramp serves to cause bending of the head suspension, in response to an outward movement of the head slider in the radial direction of the magnetic recording disk, so as to keep the head slider distanced from the surface of the magnetic recording disk. Without the support of the ramp, the head slider cannot keep distanced from the surface of the magnetic recording disk when the magnetic recording disk stands still.
When the head suspension is released from the support of the ramp in response to an inward movement of the head slider, the head slider is forced to contact the surface of the magnetic recording disk. In this case, the head slider cannot keep distanced from the surface of the magnetic recording disk without a lift resulting from an airflow generated along the surface of the rotating magnetic recording disk. If the head slider takes an inclined attitude different from a predetermined normal or horizontal attitude, the head slider cannot receive a lift enough to fly above the surface of the magnetic recording disk. The elasticity of the head suspension causes the head slider to collide against the surface of the magnetic recording disk. In particular, the head slider including a front rail extending in the lateral direction of a slider body is designed to allow generation of a larger negative pressure behind the front rail, so that the head slider tends to suffer from the collision with the assistance of the negative pressure in the aforementioned situation.
The head slider can be formed to receive a relatively larger lift even when the head slider takes the inclined attitude. This enables a reliable prevention of the collision of the head slider against the magnetic recording disk when the head suspension is released from the support of the ramp. However, in this case, the behavior of the head slider becomes sensitive to variation in the flow rate of the airflow. For example, the stability is lost in the attitude of the head slider. Specifically, the pitch angle of the head slider tends to remarkably increase as it gets closer to the rotational axis of the magnetic recording disk, since the airflow of a smaller flow rate is generated along the surface of the magnetic recoding disk at an inward position closer to the rotational axis as compared with that at an outward position closer to the outer periphery. The upstream or leading end of the head slider is more distanced apart from the magnetic recording disk at the outward position. In particular, the head slider including the front rail extending in the lateral direction tends to suffer from decrease in the negative pressure as it gets closer to the rotational axis. This involuntarily induces variation in the flying height of the head slider.